The first generation (1G) of mobile cellular communications systems were analog such as Advanced Mobile Phone Service (AMPS), Total Access Communications System (TACS), and Nordic Mobile Telephone (NMT). Primarily used for voice, they were introduced in the late 1970s and early 1980s. Starting in the 1990s, second generation (2G) systems such as GSM (Global System for Mobile Communications), TDMA (Time Division Multiple Access), and CDMA (Code Division Multiple Access) used digital encoding. Current 2G mobile communication systems are mainly geared for speech traffic and operate in symmetric full-duplex fashion. Data rates and other quality of service parameters in these systems are the same in the uplink and downlink. Real-time media can seldom be served in a 2G wireless platform.
The third generation (3G) system is defined by the International Telecommunications Union (ITU) under the IMT-2000 global framework and is designed for high-speed multimedia data and voice. Its goals include high-quality audio and video transmission and advanced global roaming, which means being able to go anywhere and automatically be handed off to whatever wireless system is available (in-house phone system, cellular, satellite, etc.). In third generation systems, data traffic, as generated by IP-based information retrieval applications, is expected to dominate. Different kinds of applications can be served by 3G systems at a certain time instance.
The characteristics of different kinds of media vary dramatically. For real time media transmission, such as video and audio, low delay is required while some kinds of errors can be tolerable. On the other hand, for non-real time media transmission, such as web access and file download, reliability is required while some levels of latency can be tolerable. Based on the different characteristics of different media streams, there are various QoS (Quality of Service) levels that are required. A key problem in a system with several services and different QoS level requirements is the derivation of a combination of these quality criteria into a single performance measure or cost function, where the combination will allow a straightforward mathematical optimization formulation.
It would be an advance in the art to provide a technique for optimizing a system with several services having different QoS level requirements for multimedia delivery over a wireless network, such as a third generation Wideband-CDMA network.